1. Field of the Invention
The present invention relates to a controlling method for an absorption refrigerator.
2. Detailed Description of the Prior Art
Generally it is necessary for improving the efficiency of an absorption refrigerator to increase the amount of heat exchanged between the low temperature heat exchanger and the high temperature heat exchanger. When the quantity of exchanged heat is increased by the expansion of surface area in the heat exchangers or by the improved thermal performance, a large temperature drop is observed for the concentrated absorption solution, which flows out of the low temperature heat exchanger. This is also accompanied with a sudden temperature drop for cooling water supplied to the absorber and the condenser. In this case a sudden temperature drop is also observed for a diluted absorption solution causing a sudden temperature drop for the concentrated absorption solution, which conducts heat exchange with the diluted absorption solution in the low temperature heat exchanger. The probability of crystallization for the concentrated absorption solution before entering the absorber is eventually increased.
For this reason, Japanese Published Unexamined Patent Application No. Hei03-20671 discloses an example of controlling the amount of heat supplied to a high temperature regenerator in a conventional absorption refrigerator when the concentration of a concentrated absorption solution flowing out of a low temperature heat exchanger exceeds a prescribed figure.
However, such controlling method focusing only on the concentration of a concentrated absorption solution flowing out of a low temperature heat exchanger does not establish a limitation for the heat supplied to a high temperature regenerator naturally when the above concentration comes below a prescribed figure. If the temperature of the concentrated absorption solution is accidentally lowered by some reasons, the concentrated absorption solution is readily crystallized, frequently resulting in the incapability of operation.
Meanwhile the above patent discloses another example, in which the control of concentration is carried out by changing the outlet temperature of the low temperature heat exchanger. This may allow unlimited supply of heat to the high temperature regenerator in spite of the excessively raised concentration of the concentrated absorption solution when the temperature of the concentrated absorption solution flowing out of the low temperature heat changer is accidentally raised by some factors such as degradation of thermal performance in the heat exchanger. Such method yields various mal-effects including drastic corrosion of metal parts in a pipeline for the absorption solution (corrosion rate quickens mainly at a section of high temperature).
Therefore, it is necessary to provide an absorption refrigerator, which should be never operated with the absorption solution exceeding a prescribed concentration, eliminating a possibility of drastic corrosion in metal parts. It should be firmly protected from crystallization in the absorption solution regardless of the operating conditions. These are the problems to be solved.
The present invention solves the above problems of the existing technologies by providing:
The first controlling method for an absorption refrigerator having a high temperature regenerator, a low temperature regenerator, a condenser, an absorber, a low temperature heat exchanger, and a high temperature heat exchanger, which are interconnected through a pipeline, wherein the concentration of a concentrated absorption solution flowing out of a low temperature regenerator into an absorber through a low temperature heat exchanger and the temperature of the concentrated absorption solution flowing out of the low temperature heat exchanger into the absorber are determined respectively, and a limitation is set up for the amount of heat supplied to the high temperature regenerator when the difference between the crystallizing temperature of the concentrated absorption solution calculated from the above concentration and the temperature of the above concentrated absorption solution comes within a prescribed figure.
The second controlling method according to the above first controlling method, wherein the concentration of the concentrated absorption solution is calculated based on the temperature of the concentrated absorption solution at the outlet of the low temperature regenerator and the condensing temperature of an employed coolant in the condenser.
The third controlling method according to the above first or the second controlling method, wherein a limitation is set up for the amount of heat supplied to the high temperature regenerator regardless of the above temperature difference when the concentration of the above concentrated absorption solution exceeds a prescribed figure.
The fourth controlling method according to the first or the second controlling method, wherein any limitation is not set up for the heat supplied to the high temperature regenerator regardless of the above temperature difference when the concentration of the above concentrated absorption solution comes below a prescribed figure.
The fifth controlling method according to the controlling methods from the first to the fourth, wherein the rotating rate of a pump for the absorption solution, which is installed on a certain place of a pipeline connecting the absorber and the high temperature regenerator through the low temperature heat exchanger, is elevated in place of, or in addition to the above-mentioned limitation on the heat supplied to the high temperature regenerator.